Backlight assembly

ABSTRACT

A backlight assembly includes a plurality of point light sources, a light guide plate (“LGP”) and a printed circuit board (“PCB”). The LGP has a light incident face in which light is incident, a side surface extending from an edge portion of the light incident face, and a fixing groove which is formed from the side surface toward an inner portion thereof. The PCB includes a point light source disposing portion in which the point light sources are disposed along a first direction, an extending portion extending from the point light disposing portion along a second direction substantially perpendicular to the first direction, and a protrusion which is fixed at an end portion of the extending portion. The protrusion of the PCB is coupled with the fixing groove of the LGP.

PRIORITY STATEMENT

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 2009-116409, filed on Nov. 30, 2009 in the KoreanIntellectual Property Office (KIPO), the contents of which are hereinincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Example embodiments of the present invention relate to a backlightassembly. More particularly, example embodiments relate to a backlightassembly capable of enhancing light efficiency and maintaining uniformdisplay luminance.

2. Description of the Related Art

Liquid crystal display (“LCD”) devices are one of the most widely usedtypes of flat panel display devices. LCD devices include a displaysubstrate on which electric field generating electrodes, such as a firstpixel electrode and a second pixel electrode, are formed, and anopposite substrate. The opposite substrate is positioned opposite to thedisplay substrate. Moreover, LCD devices include a liquid crystal (“LC”)layer interposed between the display substrate and the oppositesubstrate, and together, the two substrates and LC layer form the LCDpanel portion of the LCD device. LCD devices display images by applyingvoltages to the electric field generating electrodes in the LCD panel,which cause an electric field to be generated across the LC layer. Theelectric field controls the orientation of the LC molecules in the LClayer, which affects the polarization of light passing therethrough.

Because the LCD panel of an LCD device is a non-light-emitting devicethat is not capable of emitting light on its own, a light source isrequired for the LCD device to display images. Light sources commonlyused in LCD devices include, for example, light-emitting diodes (“LED”),cold cathode fluorescent lamps (“CCFL”), flat fluorescent lamps (“FFL”),etc.

The light source is incorporated into a backlight assembly, which isplaced next to the LCD panel. Conventional LCD devices typically employan edge illumination type backlight assembly. The edge illumination typebacklight assembly includes a plurality of LEDs and a light guide plate(“LGP”). The LEDS are disposed along a side of the LGP. In the edgeillumination type backlight assembly, the LEDs along a side of the LGPemit light, and the emitted light is incident into the LGP. The LGP thenguides the light provided from the LEDS through the LGP such that thelight is incident into the LCD panel. The distance that light travelsfrom a light emission surface of the LEDs to a side, incident surface ofthe LGP is referred to as an “incident light distance.” The incidentlight distance is not uniformly maintained due to elasticity of the LGP,which may contract or expand in accordance with a surroundingtemperature and moisture content of ambient air.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

In one aspect an edge illumination type backlight assembly in which adistance between a light emission surface of a light-emitting diode anda side surface of a light guide plate is uniformly maintained isprovided.

Accordingly, a backlight assembly includes a plurality of point lightsources, a light guide plate (“LGP”) and a printed circuit board (“PCB”)is provided. The point light sources emit light and are aligned in afirst direction. The LGP has a light incident face in which the lightsare incident, a side surface extending from an edge portion of the lightincident face, and a fixing groove which is formed from the side surfacetoward an inner portion thereof. The PCB includes a point light sourcedisposing portion in which the point light sources are disposed, anextending portion extending from the point light disposing portion alonga second direction that is substantially perpendicular to the firstdirection, and a protrusion which is fixed at an end portion of theextending portion. The protrusion of the PCB is coupled with the fixinggroove of the LGP.

According to another aspect, a backlight assembly includes a pluralityof point light sources, a light source module cover, an LGP and areceiving container. The point light sources emit light in a firstdirection. The light source module cover includes a light source fixingportion fixing the point light sources, an extending portion extendingfrom the light source fixing portion and an LGP fixing portion formed atthe extending portion. The LGP has a light incident face disposedadjacent to the point light sources, a side surface extending from ashort side of the light incident face along the first direction, a lightexit face extending from a long side of the light incident face alongthe first direction, and a light reflection face opposite to the lightexit face to diffuse and reflect light which enters the LGP at the lightincident face. The receiving container includes a bottom platesupporting the light source module cover and the LGP, and a side wallformed at an edge of the bottom plate. A fixing groove receiving the LGPfixing portion is formed at a side surface of the LGP, and the lightsource module cover is overlapped with the LGP and moves independentlyfrom the bottom plate.

Detailed descriptions of example embodiments are described in thespecification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages will become more apparent bydescribing in detailed example embodiments with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view illustrating a liquid crystal display(“LCD”) device including a conventional edge illumination type backlightassembly;

FIG. 2 is a cross-sectional view taken along a line I-I′ of the LCDdevice of FIG. 1;

FIG. 3 is a graph showing a relationship between the distance incidentlight travels for a light source module and the incident lightefficiency;

FIG. 4 is an exploded perspective view schematically showing an LCDdevice including a backlight assembly according to an exampleembodiment;

FIG. 5 is a perspective view showing a coupling relationship betweenfirst and second light source modules and a light guide plate;

FIG. 6 is an enlarged perspective view showing a portion “A” in FIG. 4;

FIG. 7A is a partial cross-sectional view taken along a line II-II′ ofFIG. 6;

FIG. 7B is a partial cross-sectional view of a backlight assemblyaccording to another example embodiment;

FIG. 7C is a partial cross-sectional view of a backlight assemblyaccording to another example embodiment;

FIGS. 8A and 8B are partial perspective views of a backlight assemblyaccording to another example embodiment;

FIG. 9 is a perspective view of a backlight assembly according toanother example embodiment;

FIG. 10 is a plan view showing a mold frame of FIG. 4; and

FIG. 11 is a partial enlarged perspective view showing a portion “B” inFIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which example embodiments are shown.The present invention may, however, be embodied in many different formsand should not be construed as limited to the example embodiments setforth herein. Rather, these example embodiments are provided so thatthis disclosure will be thorough \, and will convey the scope of thepresent invention to those skilled in the art. In the drawings, thesizes and relative sizes of layers and regions may be exaggerated forclarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layer,or intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the present disclosure.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s), as illustrated in the figures. It will be understood thatthe spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below, depending on the orientation. The devicemay be otherwise oriented (rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein interpretedaccordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, etc. but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, etc. and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the relevant art. It will be further understoodthat terms, such as those defined in commonly used dictionaries, shouldbe interpreted as having a meaning that is consistent with their meaningin the context of the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Hereinafter, example embodiments will be explained in detail withreference to FIGS. 1 to 10.

FIG. 1 is a perspective view illustrating a liquid crystal display(“LCD”) device 100 including a conventional edge illumination typebacklight assembly 191. FIG. 2 is a cross-sectional view taken along aline I-I′ of the LCD device 100 of FIG. 1.

Referring to FIGS. 1 and 2, a light guide plate (“LGP”) 150 has a lightincident face 151 in which light generated from a light source module170 is incident, an opposite face 152 opposite to the light incidentface 151, a light exit face 153 connecting the light incident face 151and the opposite face 152 to emit lights toward an LCD panel, and areflection face 154 opposite to the light exit face 153.

The LGP 150 guides light generated by the light source module 170 fromthe light source module 170, which is disposed at a first side of theLGP 150, toward the LCD panel. Light that is incident at a first sidesurface of the LGP 150 passes into and through the LGP 150 and arrivesat an upper surface or a lower surface of the LGP 150. When the lightarrives at the upper surface or lower surface of the LGP 150 at anincident angle to the surface that is no less than a threshold angle ofthe LGP 150, such light is not emitted toward an outside of the LGP 150,but instead is fully reflected at the surface of the LGP 150. Suchreflected light is uniformly dispersed in an inner portion of the LGP150. In this case, the LGP 150 may have a plate shape. The LGP 150 mayinclude an optically transparent material such as a plastic basedmaterial. Examples of materials appropriate for the LGP 150 includeacrylic resin such as polymethyl methacrylate (PMMA) and poly carbonate(PC) having a heat resistance superior to that of the PMMA.

The light source module 170 includes a plurality of point light sources170 which emit light to a first side surface of the LGP 150, and a pointlight source printed circuit board (“PCB”) 172 in which a plurality ofcircuit patterns that apply a driving power to the point light sources170 are formed. One of the point light source PCBs 172 is disposed at afirst side of the LGP 150, and the other of the point light source PCBsis disposed at a second side of the LGP 150. The point light source 171may be a light-emitting diode (“LED”). In this case, the light sourcemodule 170 may include a plurality of LEDs 171 and a PCB 172 for drivingthe LEDs 171. The LEDs 171 are mounted on the PCB 172. A plurality ofcircuit patterns (not shown), which are electrically connected to eachof the LEDs 171 to apply a driving current to the LED 171, are formed onthe PCB 172. The PCB 172 may have a rectangular shape that has two shortsides along a first direction DI1 and two long sides along a seconddirection DI2.

The LEDs 171 are disposed on the PCB 172 to be spaced apart from eachother along a long side of the PCB 172. For example, each of the LEDs171 may include a white LED. For another example, each of the LEDs 171may include a red LED, a green LED and a blue LED. In this case, the redLED, the green LED and the blue LED are grouped to emit a white light.For convenience of description, it will be assumed that the LED 171 is awhite LED.

In a structure in which the light source module 170 and the receivingcontainer 180 are affixed to each other, because the LGP 150 maycontract or expand in accordance with changes in the surroundingtemperature and moisture content, the distance incident light travelsfrom the LED 171 to the light incident face 151 of the LGP 150 on whichlight is incident can be variable.

The distance incident light travels from the LED 171 to the lightincident face 151 (the “incident light distance”) is preferablyoptimized in accordance with light incident efficiency, which is theratio of an amount of light emitted by the light source to the amount oflight that is incident into the face of the LGP 150 and with the stateof the LGP 150 under a set of conditions, for instance temperature ormoisture. However, although the incident light distance may be optimizedfor a particular set of conditions, the LGP 150 can contract or expanddue to changes in external variables such as surrounding temperature ormoisture content, so that an optimum distance is not maintained but isvariable. Particularly, when the thickness of the LGP 150 is reduced, sothat the LGP is relatively thin, the LGP 150 is more affected by theexternal variables, so that it is impossible to control the incidentlight distance. For example, when the LGP 150 absorbs heat generatedfrom the LED 171, or a volume of a face in which light is incident,including light incident face 151 of the LGP 150, is expanded due to anincrease of moisture content, light incident face 151 moves relative toan upper face 178 of the LED 171, so that the incident light distance isdecreased with respect to the optimum distance. On the contrary, whenthe volume of the portion of the LGP on which light is incident, such aslight incident face 151, is contracted due to a low surroundingtemperature or a low level of moisture content, the incident lightdistance is increased with respect to the optimum distance. When theincident light distance is gradually decreased, light incidentefficiency may be increased.

FIG. 3 is a graph showing light incident efficiency in accordance withincident light distance between the upper face 178 of the LED 171disposed at the light source module 170 and the light incident face 151of the LGP 150. The light incident efficiency is denoted as a ratio ofamount of the light incident into light incident face 151 of the LGP 150with respect to amount of the light exiting the light source 170. Theincident light distance is in inverse proportion to the light incidentefficiency. As shown in FIG. 3, the ratio of light incident into lightincident face 151 is increased when the incident light distance isgradually decreased, and the light incident efficiency is rapidlydecreased when the incident light distance is gradually increased. Thus,when light incident face 151 of the LGP 150 is disposed close to the LED171, so as to enhance light incident efficiency of the LCD device 100,light incident efficiency may be increased.

However, in this case, the LGP 150 is expanded due to heat generatedfrom the LED 171, so that light incident face 151 of the LGP 150 maycontact a light emission surface 178 of the LED 171. As a result, theLED 171 may be damaged by mutual friction between light incident face151 of the LGP 150 and the light emission surface 178 of the LED 171. Inaddition, reliability problems such as deterioration of display qualitymay be caused when portion LGP 150 in which light is incident heats andcondenses, so that it becomes bent, or an end portion of an opticalsheet disposed at the portion of the LGP 50 in which light is incidentmay become bent or wrinkled. The bending and/or wrinkling of the LGP 50or optical sheet disposed on the LGP 50 may cause to light leakage orluminance disuniformity, and thus result in deterioration of displayquality. That is, the light incident efficiency and the reliabilityproblem according to the incident light distance are in a trade-offrelationship. Thus, when an optimum incident light distance whichsatisfies the light incident efficiency of the light source and thereliability of the LCD device 100 is obtained, it is preferable that theoptimum incident light distance is uniformly maintained.

FIG. 4 is an exploded perspective view schematically showing a liquidcrystal display device 200 including a backlight assembly according toan example embodiment. The LCD device 200 of the present exampleembodiment includes substantially identical elements of the LCD device100 of FIG. 1 except for a structure of the backlight assembly 191. Thatis, the LCD panel 200 according to the present example embodimentincludes an LCD panel assembly 120 and a backlight assembly 191.

The LCD panel assembly 120 includes an LCD panel 123, a chip filmpackage 126, a source printed circuit board (“PCB”) 128, etc.

The LCD panel 123 includes a lower display plate 122, an upper displayplate 124 opposite to the lower display plate 122, and a liquid crystallayer (not shown) is interposed between the lower display plate 122 andthe upper display plate 124. The LCD panel 123 is disposed on thebacklight assembly 191 to display image information by using lightprovided from the backlight assembly 191.

The chip film package 126 may be connected to data lines (not shown)formed on the lower display plate 122 to provide each of the data lineswith a data driving signal. A gate driving part may be connected to eachof gate lines (not shown) formed on the lower display plate 122 toprovide each of the gate lines with a gate driving signal. For oneexample, the gate driving part may be formed in an integrated circuit.For another example, the gate driving part may be formed in the chipfilm package 126. Alternatively, various driving elements processing agate driving signal which is input to the data driving part and a datadriving signal which is input to the chip film package 126 may bemounted on the source PCB 127.

The backlight assembly 191 includes optical sheets 140, a mold frame130, a light guide plate 150, a reflection plate 160, a first lightsource module 170 a, a second light source module 170 b (FIG. 5), alower receiving container 180, etc. The optical sheets 140, thereflection plate 160 and the mold frame 130 will be described later.

FIG. 5 is a perspective view showing a coupling relationship betweenfirst and second light source modules 170 a and 170 b and an LGP 150(FIG. 1).

Referring to FIGS. 4 and 5, the first and second light source modules170 a and 170 b are respectively disposed at a first portion of the LGP150 and a second portion facing the first portion of the LGP 150 along afirst direction DI1. In a light disposing structure, in order to emituniform lights to an entire of display panel, the LGP 150 may be formedso that it is flat and has a uniform thickness. Alternatively, a shapeof the LGP 150 is not limited thereto, and the LGP may employ variousshapes.

The LGP 150 has a light incident face 151 in which light generated froma light source module 170 is incident, an opposite face 152 opposite tothe light incident face 151, a light exit face 153 connecting the lightincident face 151 and the opposite face 152 to emit light toward an LCDpanel, and a reflection face 154 opposite to the light exit face 153.Hereinafter, a description for a structure of the LGP 150 as previouslydescribed in reference to FIG. 1 will be omitted. The LGP 150 includes afirst side surface 155 and a second side surface 156, which connect thelight incident face 151 and the opposite face 152. The light incidentface 151 and the opposite face 152 with respect to the first lightsource module 170 a may also correspond to an opposite face and a lightincident face, respectively, with respect to the second light sourcemodule 170 b disposed at a second side of the LGP 150.

A plurality of diffusion patterns (not shown) is further formed on atleast one surface of reflection face 154 and light exit face 153 of theLGP 150 so as to emit light propagating within the inner portion of theLGP 150 toward the LCD panel 123 positioned at an upper portion of theLGP 150. The diffusion patterns, which are formed at a first surface ofthe LGP 150 to make the luminance of light emitted from the LGP 150uniform, may be formed to have different sizes and densities inaccordance with their distance from the first and second light sourcemodules 170 a and 170 b. For example, a density of the diffusionpatterns or a size of the diffusion patterns is increased as thediffusion patterns are spaced further from the first and second lightsource modules 170, so that luminance of light emitted from the lightexit face 153 may be uniform. The diffusion patterns may be formedthrough a silk screen printing process or a laser process, however, thepresent example embodiment is not limited to the process for formingdiffusion patterns. For example, it is possible that fine grooves orfine protrusions are formed on the LGP 150 to form the diffusion patternhaving an identical action and effect to the diffusion pattern formedthrough a silk screen printing process or laser process.

In FIG. 5, each of the first and second light source modules 170 a and170 b includes a plurality of point light sources which emits light to afirst side surface of the LGP 150, and a point light source PCB in whicha plurality of circuit patterns applying a driving power to the pointlight sources is formed.

The PCB 172 for driving the LED 171 includes a base substrate, a circuitpattern formed on the base substrate, and an insulation layer (notshown) which prevents an electrical short between the circuit patterns.The circuit pattern is formed from an electrical material which ispatterned to apply a driving current to the LED 171. For example, thebase substrate may be configured in a rigid plate or a flexible filmtype in accordance with thickness and flexibility thereof. Moreover, thebase substrate may be supported by a metal plate (not shown) toeffectively irradiate heat generated from the LED 171. In this case, themetal plate may also provide mechanical stability to the light sourcemodule 170.

According to an example embodiment, in order to have an incident lightdistance of each of the light source modules 170 be uniform, aprotrusion 174 is formed on an upper surface 173 of the PCB 172 of thelight source module 170. As shown in FIG. 5, it is assumed that the PCB172 of the first light source module 170 a is a plane having a shortside of a first direction DI1 and a long side of a second direction DI2,the protrusion 174 may be formed at an adjacent portion adjacent to twoshort sides of the PCB 172 of the first light source module 170 a.

For example, the protrusion 174 may be positioned so that it is towardthe LGP 150 from the PCB 172 on which the LED 171 is disposed. Moreover,the protrusion 174 may be disposed outside of a region in which the LEDs171 are aligned, that is on a portion of PCB 172 that is outside of theportion that the LED 171 disposed at the most outer area of the lightsource module 170 is positioned. Furthermore, the protrusion 174 may beformed on the PCB 172 of the second light source module 170 b in asymmetric manner with respect to the protrusions 174 of the PCB 172 ofthe first light source module 170 a.

The protrusion 174 may be formed on the PCB 172 in a soldering processthrough a surface mounting method. In this case, the protrusion 174 mayinclude a metal material which is capable of soldering. Alternatively, apenetration hole (not shown) is formed through the PCB 172 where theprotrusion 174 is formed, and then a coupling member is coupled throughthe penetration hole to form the protrusion 174. In this case, theprotrusion 174 may include a resin material.

The number of the protrusion 174 formed on the PCB 172 may be set withinoptical characteristics of the LGP 150. For example, a single protrusion174 may be formed at two end portions of the PCB 172, respectively. Inthe present example embodiment, it is described that the shape of theprotrusion 174 is a cylindrical shape. Alternatively, the shape of theprotrusion 174 may be various shapes such as a rectangular shape, ahexagon pillar shape, etc.

In order to radiate heat generated from the LED 171, a heat radiatingplate (not shown) of a heat conductive metal material such as copper(Cu), aluminum (Al), etc., may be further attached to the PCB 172 of anexample embodiment. A heat radiating pattern (not shown) may be formedon the heat radiating plate so as to obtain uniform heat radiation.Moreover, in order to allow a rear surface of the PCB 172, which isdescribed later, to move smoothly a heat conductive tape having anon-attaching characteristic may be attached on a rear surface of thePCB 172. Furthermore, in order to allow a rear surface of the PCB 172,which is described later, to move smoothly a thermal grease having highthermal conductivity may be coated on the rear surface of the PCB 172.

Hereinafter, referring again to FIGS. 4 and 5, in order to uniformlymaintain an incident light distance of the light source module 170, afixing groove 157 coupled with the protrusion 174 will be explained.

Referring to FIG. 5, the fixing groove 157 (as represented by fixinggrooves 157 a, 157 b, 157 c and 157 d) is formed at an end portion of aside surface 155 and 156 connecting the light incident face 151 and theopposite face 152 of the LGP 150. In this case, the fixing groove 157 isformed at a first end portion of the first side surface. The fixinggroove 157 may also be formed at two end portions of the first sidesurface. That is, the fixing grooves 157 may be formed at a positionspaced apart from a tangent line in which the light incident face 151and the first side surface are met with each other or the opposite face152 and the first side surface are met with each other.

The fixing groove 157 is positioned so that an incident light distancewhich light incident efficiency of the light source module 170 ismaximized. When the fixing grooves respectively formed adjacent to thelight incident face 151 and the opposite face 152 are denoted as a firstfixing groove 157 a and a second fixing groove 157 b, the first andsecond fixing grooves 157 a and 157 b may be disposed in a symmetricmanner with respect to an imaginary line crossing a center of the LGP150 in parallel with the second direction DI2.

When the light source module 170 is disposed at two ends of the LGP 150,the first fixing groove 157 a and the third fixing groove 157 c may beformed through the LGP 150 with respect to the first light source module170 a, and the second fixing groove 157 b and the fourth fixing groove157 d may be formed through the LGP 150 with respect to the second lightsource module 170 b. FIG. 6 is an enlarged perspective view showing aportion “A” circled in FIG. 4. In FIG. 6, the coupling relationshipbetween a protrusion 174 and a fixing groove 157 is enlarged and shown.FIG. 7A is a partial cross-sectional view taken along a line II-II′ ofFIG. 6.

In FIG. 4, it is assumed that the protrusion 174 of the first lightsource module 170 a corresponding to the first fixing groove 157 a is afirst protrusion 174 a. The first fixing groove 157 a corresponding tothe first protrusion 174 a may have a width W2 along the first directionDI1 and a length L2 along the second direction DI2. In this case, thelength L2 is greater than the width W2.

The LGP 150 is expanded in the first and second directions DI1 and DI2due to surroundings thereof. When the LGP 150 is expanded in the firstdirection DI1, the LGP 150 is coupled and fixed with the firstprotrusion 174 a, attached to PCB 172, so that the PCB 172 moves withthe expansion of the LGP 150, and the incident light distance may bemaintained. When the LGP 150 is expanded in the second direction DI2,the LGP 150 is moves freely over the PCB 172. Thus, bending andcontraction of the LGP 150 may be prevented. Therefore, in order toensure there is room for the LBP 150 to expand or contract in the seconddirection DI2, the length L2 is typically greater than the width W2.

In the backlight assembly 190, a width W1 of the first protrusion 174 amay be substantially equal to the width W2 of the first fixing groove157 a, so that the first protrusion 174 a contacts with walls of thefirst fixing groove 157 a so that they are coupled together.Alternatively, the width W1 of the first protrusion 174 a may beslightly smaller than the width W2 of the first fixing groove 157 a.When the LGP 150 is expanded in the first direction DI1 by surroundingtemperature, moisture of ambient air and so on, the PCB 172 on which theLEDs 171 are mounted may be also moved by the expansion of the LGP 150due to a coupling of the first protrusion 174 a and the first fixinggroove 157 a, so that the incident light distance may be uniformlymaintained.

Because the PCB 172 is not fixed to a bottom plate 181 of a lowerreceiving container 180, an interval distance between the light incidentface 151 of the LGP 150 and a light emission surface 178 of the LED 171,that is, an incident light distance may be substantially maintained in auniform manner. That is, a lower face of the PCB 172 moves independentlyfrom the bottom plate 181 of the lower receiving container 180 and movesdependently from the LGP 150. Thus, a distance between the lightincident face 151 of the LGP 150 and a light emission surface 178 of theLED 171 is maintained in a uniform manner within an error rangeaccording to a variation of temperature and moisture, so that luminanceuniformity or luminance intensity at a light exit face of the LGP 150may be maintained in a uniform manner.

In addition, the widths W1 of the protrusion 174 and the widths W2 ofthe fixing grooves 157 may be set to have an optimum relationship withrespect to a coupling tolerance. For example, the width of the fixinggroove 157 formed through the LGP 150 is substantially greater than thewidth of the protrusion 174. In this case, the width of the fixinggroove and the width of protrusion may be obtained in consideration withexpanding ratio of the PCB 172.

The first fixing groove 157 a according to an example embodiment isrecessed from the first side surface 155 toward an inner portion of theLGP 150, as shown in FIG. 6. The first fixing groove 157 a may have afirst inner face 157 a 1, a second inner face 157 a 2 facing the firstinner face 157 a 1, and a connection face 157 a 3 connecting the firstand second inner faces 157 a 1 and 157 a 2.

The fixing groove 157 may, for instance, be a hole that penetrates theLGP 150 in an area adjacent to a side surface of the LGP 150, so thatthe protrusion 174 can fit into the hole. Alternatively, as shown inFIGS. 4, 5 and 6, the fixing groove 157 may be a groove, rather than ahole, so as to enhance assembly simplicity. The connection face 157 a 3may be a curved surface in which a portion of an external surface of thefirst protrusion 174 a is engaged. In the present example embodiment,the connection face 157 a 3 may have an arch type curved surface tocorrespond with the first protrusion 174 a, which has a cylindricalshape. The connection face may have a planar surface or a curved surfaceof various shapes, and it is not limited to the present exampleembodiment.

The first protrusion 174 a may be formed at a position on the LGP 150that corresponds to the first fixing groove 157 a. That is, the firstprotrusion 174 a may be positioned on the LGP 150 at an outer area(i.e., a dead zone) of a radiation angle of the light emitted from theLED 171 that is positioned at the most outer area of the light sourcemodule 170. In case that the PCB has a narrower width along directionDI1, the first protrusion 174 a may be more closely positioned to anarea adjacent to light incident face 151. Moreover, in order to disperselight incident into the LGP 150, a plurality of patterns may be furtherformed on a surface area of the first fixing groove 157 a that isadjacent to the first protrusion 174 a. In this case, the firstprotrusion 174 a and the first fixing groove 157 a are covered by themold frame 130, which is disposed over the first fixing groove 157 a, sothat the patterns of the surface area of the first fixing groove 157 ado not affected the display quality.

FIG. 7A is a partial cross-sectional view taken along a line II-IF ofFIG. 6. That is, FIG. 7A shows a coupling relationship between the firstprotrusion 174 a and the first fixing groove 157 a.

FIG. 7B is a partial cross-sectional view of a backlight assemblyaccording to another example embodiment.

The backlight assembly of the present example embodiment issubstantially the same as the backlight assembly of FIGS. 6 and 7Aexcept for at least a coupling structure of a protrusion 174 and afixing groove 157, and thus any repetitive detailed explanation mayhereinafter be omitted.

The first protrusion 174 a of the present example embodiment may have ashape in which an elastic member 174-1, such as a spring, is disposed atan exterior surface of a protrusion body. A first end portion of theelastic member 174-1 contacts with inner surfaces 157 a 1 and 157 a 2 ofthe first fixing groove 157 a, so that the processing tolerance duringformation of the first fixing groove 157 a of the LGP 150 may bereduced. In this case, the first protrusion 174 a contacts the firstfixing groove 157 a such that there is elasticity between the firstprotrusion 174 a and the first fixing groove 157 a. As a result, anincident light distance of the light source module 170 may bemaintained. Moreover, since the elastic member 174-1 is employed withthe first protrusion 174 a, a displacement of the PCB and a displacementof the LGP will be substantially equal to each other, even though thePCB is contracted. Therefore, the incident light distance may be easilymaintained.

FIG. 7C is a partial cross-sectional view of a backlight assemblyaccording to still another example embodiment.

The backlight assembly of the present example embodiment issubstantially the same as the backlight assembly of FIGS. 6 and 7Aexcept for at least a coupling structure of a protrusion 174 and afixing groove 157. Thus, identical reference numerals are used in FIG.7C to refer to components that are the same or like those shown in FIGS.6 and 7A, and thus any repetitive detailed explanation may hereinafterbe omitted.

The first protrusion 174 a of the present example embodiment includes aflat plate shaped elastic member having protruding parts that face eachother. The flat plate shaped elastic member includes a base portion 175a formed on an upper face of the PCB 172, a first protruding part 175 bthat protrudes from the base portion 175 a and extends to a first innerside surface 157 a 1 of the first fixing groove 157 a, and a secondprotruding part 175 c that protrudes from the base portion 175 a andextends to a second inner side surface 157 a 2 of the first fixinggroove 157 a. Each of the first and second protruding parts 175 b and175 c has a bent portion 175 c that contacts the first and second innerside surfaces 157 a 1 and 157 a 2. A shape of the flat plate shapedelastic member is not limited to the example embodiment illustrated inFIG. 7C, and it may be formed in various shapes. The bent portion 176 ofthe flat plate shaped elastic member contacts the first and second innerside surfaces 157 a 1 and 157 a 2 of the first fixing groove 157,thereby preventing development of an interval between the firstprotrusion 174 a and the first fixing groove 157 a that may occur due toa processing tolerance of the fixing groove 157 or external impact.

FIGS. 8A and 8B are partial perspective views of a backlight assemblyaccording to further still another example embodiment.

The backlight assembly of FIGS. 8A and 8B is substantially the same asthe backlight assembly of FIG. 4 except for at least a couplingstructure of a light source module 170 and a light guide plate 150, andthus any repetitive detailed explanation may hereinafter be omitted.

The backlight assembly of FIG. 8A may further include a light sourcemodule cover 177 disposed at a rear surface of the light source module170 including a plurality of light-emitting diodes 171 and a PCB 172.

The light source module 170 and the light source module cover 177 areaffixed through an adhesive tape, a screw, and so on. The light sourcemodule cover 177 may be a metal plate which easily absorbs heat emittedfrom the LEDs and delivers the excess heat to an external portionthereof. A reflective material such as silver (Ag) may also be coated onthe metal plate. In this case, the coated silver may reflect a whitelight emitted from the LED toward the light incident face 151 of the LGP150 to enhance reflection efficiency.

In the PCB 172 of the present example embodiment, a first face in whicha plurality of LEDs 171 are arranged in parallel with each other to facethe light incident face 151 of the LGP 150.

FIG. 8B shows a structure of the light source module cover 177.Referring to FIG. 8B, the light source module cover 177 includes asupport portion 177-1 in which the PCB 172 is disposed to fix the LEDs171, a bottom portion 177-2 extending from an edge portion of thesupport portion 177-1, so as to be partially overlapped with thereflection face 154 of the LGP 150, and a coupling portion 177-3 thatextends from a first portion of the support portion 177-1, so as to beformed along a first side wall 155 of the LGP 150.

The coupling portion 177-3 includes an LGP fixing portion 177-4extending along an inner face 158-1 of a coupling groove 158 of the LGP150 as shown in FIG. 8A. Since the coupling portion 177-3 of the lightsource module cover 177 is coupled with the coupling groove 158, anincident light distance of the light source module 170 may be maintainedin a uniform manner. Shapes of the coupling portion 177-3 and thecoupling groove 158 are not limited to that example embodiment of FIGS.8A and 8B, and it may be deformed in various shapes.

FIG. 9 is a perspective view of a backlight assembly according to stillanother example embodiment.

Referring to FIG. 9, the backlight assembly of the present exampleembodiment is substantially the same as the backlight assembly of FIG. 4except that a PCB 172 further includes a metal support structure 179,and thus any repetitive detailed explanation may hereinafter be omitted.

The PCB 172 of the backlight assembly of the present example embodimentmay further include a metal support structure 179. The metal supportstructure 179 includes a horizontal portion 179 a overlapping with thereflection face 154 of the LGP 150, and a vertical portion 179 b bentfrom the horizontal portion 179 a so as to be overlapped with the firstand second side surfaces 155 and 156 of the LGP 150. In this case, aprotrusion 174 may be formed on an edge portion of the horizontalportion 179 a of the metal support structure 179 to be coupled with thefixing groove 157 of the LGP 150. The shape and position of theprotrusion 174 are substantially the same as in the previous exampleembodiment, and thus a detailed description thereof will be omitted.Accordingly, the protrusion 174 is formed on the metal support structure179 and the horizontal and vertical portions cover the LGP 150, therebyfixing the LGP 150 in a stable manner.

FIG. 10 is a plan view showing a mold frame of FIG. 4.

FIG. 11 is a partial enlarged perspective view showing a portion “B” inFIG. 10.

Hereinafter, the reflection plate 160, the optical sheets 140 and alower receiving container 180 of the backlight assembly 190 will beexplained in detail with reference to FIGS. 4, 10 and 11.

The reflection plate 160 is disposed between the reflection face 154 ofthe LGP 150 and the bottom plate 181 of the lower receiving container180 to reflect light exiting through the reflection face 154 of the LGP150 toward an upper portion thereof. The penetrating hole 161 (see FIG.4) is formed in a portion corresponding to a position where theprotrusion 174 is positioned on the PCB 172. The protrusion 174 isinserted through the penetrating hole 161, thereby enhancing assemblysimplicity of the backlight assembly. The optical sheets 140 aredisposed between the backlight assembly 191 and the LCD panel assembly120 to increase light efficiency. Each of the optical sheets 140 mayinclude an optical sheet body 141 and an optical sheet guide groove 142formed at an edge of the optical sheet. The optical sheet guide groove142 is coupled with a guide protruding portion of a mold frame 130(which will be described later) to fix the optical sheet body to play arole of preventing movement of the optical sheet body. A structure ofthe optical sheets 140 is not limited to that example embodiment, andthe structure of the optical sheets 140 may be varied in accordance witha specification of a display device. The lower receiving container 180may include a bottom plate 181 having a rectangular shape and aplurality of side walls that extend from edges of the bottom plate 181to form a receiving space. The side walls may include a first side wall181 and a second side wall 183 that are parallel to each other along thefirst direction DI1 to face each other, a third side wall 184 and afourth side wall 185 that are parallel to each other along the seconddirection DI2 to face each other. The PCB 172, the reflection plate 160,the LGP 150 and the optical sheets 140 are sequentially disposed in thereceiving space of the lower receiving container 180.

In FIG. 10, the mold frame 130 includes a side portion 133 of arectangular frame shape, a first support portion 134 (FIG. 11) thatextends from the side portion 133 toward an inner portion thereof and asecond support portion 135 that extends from the side portion 133 towardan inner portion thereof. An LCD panel is disposed on a first face ofthe first support portion 134, and optical sheets 140 and the LGP 150are disposed on a second face of first support portion 134. The secondsupport portion 135 is formed on a second face of the first supportportion 134 to prevent the optical sheets 140 and the LGP 150 fromshifting. The thickness of the second support portion 135 may besubstantially equal to the total sum of the thickness of the opticalsheets 140 and the thickness of the LGP 150. A guide protruding part 136protruded from the second support portion 135 toward an inner portion ofthe mold frame 130 may control movement of the optical sheets 140 andthe LGP 150. For example, the guide protruding part 136 of the moldframe 130 is inserted into a guide groove 142 formed through an endportion of the optical sheets 140 and a guide groove 159 formed throughan end portion of the LGP 150.

The reflection plate 160 is disposed on the second support portion 135.In order to fix the reflection plate 160, a fixing pin 131 may be formedon a first face of the second support portion 135. In an exampleembodiment, it is explained that the fixing pin 131 is formed on theguide protruding part 136 of the second support portion 135; however, itis not limited to the present example embodiment. For example, thefixing pin 131 may be disposed at a predetermined position of the secondsupport portion 135. The fixing pin 131 is inserted into an insert pin162 of the reflection plate 160. Moreover, an additional fixing pin 20that protrudes opposite to the reflection plate 160 may be formed on thefirst support portion 134 or the second support portion 135. In thiscase, the additional fixing pin 20 may suppress the reflection plate 160to fix the reflection plate 160 to the bottom plate 181 of the lowerreceiving container 180.

A fixing protruding part 137 is formed at a corner portion of the moldframe 130, and protrudes from the second support portion 135substantially in parallel with the side portion 133. An insertion spaceof a U-shape is defined between the fixing protruding part 137 and theside portion 135. A third side wall 184 and a fourth side wall 185 ofthe lower receiving container 180 are inserted into the insertion spaceto be fixed thereto. According to an example embodiment, the lowerreceiving container 180 and the mold frame 130 are coupled with eachother to receive the optical sheets 140, the LGP 150 and the reflectionplate 160. The first and second side walls 182 and 183 of the lowerreceiving container 180 are coupled with the mold frame 130 in a hookmethod. The third and fourth side walls 184 and 185 of the lowerreceiving container 180 are inserted into the insertion space of themold frame 130, so that a coupling force between the mold frame 130 andthe lower receiving container 180 may be sufficiently secured.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the novel teachings and advantages of thepresent invention. Accordingly, all such modifications are intended tobe included within the scope of the present invention as defined in theclaims. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific example embodiments disclosed, and thatmodifications to the disclosed example embodiments, as well as otherexample embodiments, are intended to be included within the scope of theappended claims. The present invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. A backlight assembly comprising: a plurality of point light sourcesthat emit light and are aligned along a first direction; a light guideplate (“LGP”) having a light incident face into which the light isincident, a side surface extending from an edge portion of the lightincident face, and a fixing groove which is formed in the side surface,the fixing groove extending toward an inner portion of the LGP; and aprinted circuit board (“PCB”) comprising a point light source disposingportion in which the point light sources are disposed, an extendingportion extending from the point light disposing portion along a seconddirection that is substantially perpendicular to the first direction,and a protrusion which is fixed at an end portion of the extendingportion, wherein the protrusion of the PCB is coupled with the fixinggroove of the LGP.
 2. The backlight assembly of claim 1, wherein thefixing groove comprises two inner faces which are each extended from theside surface of the LGP toward the inner portion thereof and which faceeach other, and a connection face which connects to the two inner faces.3. The backlight assembly of claim 2, wherein the connection face has acurved surface.
 4. The backlight assembly of claim 3, wherein theprotrusion comprises an exterior face and a portion of the exterior faceof the protrusion contacts the connection face of the fixing groove. 5.The backlight assembly of claim 2, wherein the protrusion comprises aflat shaped elastic member having a base portion formed at a firstsurface of the PCB and a first protruding portion and a secondprotruding portion that each extend from the base portion along adirection of the inner faces, respectively.
 6. The backlight assembly ofclaim 5, wherein the first protruding portion and the second protrudingportion are disposed to face with each other, and portions of the firstand second protruding portions contact with the inner faces.
 7. Thebacklight assembly of claim 2, wherein the protrusion comprises anelastic member on an exterior face thereof, and a first end portion ofthe elastic member contacts an interior face of the fixing groove. 8.The backlight assembly of claim 1, wherein a width of the protrusionalong the second direction is no more than a width of the fixing groovealong the second direction.
 9. The backlight assembly of claim 1,wherein a length of the protrusion along the first direction is smallerthan a length of the fixing groove along the first direction.
 10. Thebacklight assembly of claim 1, wherein the LGP has a thickness, and aheight of the protrusion is smaller than or equal to the thickness ofthe LGP.
 11. The backlight assembly of claim 1, further comprising areflection plate disposed between the PCB and a first face of the LGP,wherein the reflection plate has a hole through which the protrusionpenetrates.
 12. The backlight assembly of claim 1, wherein the PCBfurther comprises a metal support structure in which the protrusion isformed therethough.
 13. The backlight assembly of claim 12, wherein themetal support structure comprises: a horizontal portion overlapped witha light reflection face of the LGP; and a vertical portion extendingfrom the horizontal portion to be overlapped with the side surface ofthe LGP.
 14. A backlight assembly comprising: a plurality of point lightsources that emit light in a first direction; a light source modulecover comprising a printed circuit board (PCB) fixing the point lightsources, an extending portion extending from the PCB and a light guideplate (“LGP”) fixing portion formed at the extending portion; an LGPhaving a light incident face disposed in adjacent to the point lightsources, a side surface extending from a short side of the lightincident face along the first direction, a light exit face extendingfrom a long side of the light incident face along the first direction,and a light reflection face opposite to the light exit face to diffuseand reflect lights which incident at the light incident face; and areceiving container comprising a bottom plate supporting the lightsource module cover and the LGP, and a side wall formed at an edge ofthe bottom plate, wherein a fixing groove receiving the LGP fixingportion is formed at the side surface of the LGP, and the PCB isoverlapped with the LGP and moves independently from the bottom plate.15. The backlight assembly of claim 14, wherein the extending portion ofthe light source module cover is overlapped with the light reflectionface of the LGP.
 16. The backlight assembly of claim 15, wherein the LGPfixing portion of the light source module cover is fixed at an edge ofthe extending portion.
 17. The backlight assembly of claim 16, whereinthe LGP fixing portion is disposed closer to an edge of the light sourcemodule cover than the point light source is disposed in an outer area ofthe LGP.
 18. The backlight assembly of claim 16, wherein the pluralityof point light sources has a dispersion angle that forms a dark areaadjacent to the light incident face, and the LGP fixing portion isdisposed at the dark area.
 19. The backlight assembly of claim 14,wherein the extending portion of the light source module cover isoverlapped with the side surface of the LGP.
 20. The backlight assemblyof claim 19, wherein the LGP fixing portion formed at the extendingportion of the light source cover is fully inserted through the fixinggroove of the LGP.